PRODIGY(R) interactive personal service
INTRODUCTION
You may have recently read about data from other files
appearing inside the STAGE. This is a harmless side effect
of DOS file operations and the process by which the PRODIGY
STAGE is created. On the following screens you'll find a
discussion of your STAGE.DAT file.
If you're interested in the details, please read on. I think
you'll be more comfortable once you've read the facts.
Harold Goldes (CBXH97A)
Technical Editor, PRODIGY Star
READING MY HARD DISK?
The occurrence of "non-PRODIGY" data within the disk space
used by the STAGE has prompted some to speculate that
PRODIGY can gain access to that information or other
information on a member's hard disk. Here are the facts:
The PRODIGY software does not examine a member's
hard disk as a whole. It does not read files created
by other software. It does not read data other than
its own. It does not upload files to do this. The
PRODIGY software confines its file operations to a
limited and well defined section of your disk: The
PRODIGY directory.
ABOUT THE STAGE
When you install the PRODIGY software on your computer we
create a unique file on your floppy or hard disk:
STAGE.DAT. The STAGE (or STAGE.DAT as it appears in your
directory or folder) is a "container". What does it hold?
The STAGE contains frequently used information and
instructions that make up PRODIGY applications
("applications" refers to the individual activities
available to you on the service; FIND and the Movie Guide,
are examples).
LOCAL STORAGE
Placing portions of applications on the STAGE (and not in
other more remote parts of our network) puts them close to
you. Without a storage structure like the STAGE, key
components of an application would be sent to your computer
whenever you visited the application. This adds
transmission time. Placing them on your computer saves
time. When you install the DOS version of the PRODIGY
software, you have the choice of creating the STAGE in a
range of sizes from about 160Kb to 950Kb. For Macintosh
users there is one size: 200,064 bytes.
STAGE SIZES
If a member installs to a floppy disk(s), the STAGE may
vary in size. These intermediate sizes depend on several
factors including the capacity of the disk and the version
of DOS. Once it's been created, the STAGE never changes its
size. But the date and time stamp on the STAGE does change
and is updated at the end of every PRODIGY session. This
reflects the fact that during your session we read PRODIGY
content from it and write updated PRODIGY content to it.
To improve performance during your session, certain
frequently used parts of the service are always "staged". A
larger STAGE, should you choose one, permits a growing
inventory of applications to reside on your computer.
Because our software adapts itself to you, some of the
content you use regularly can become staged.
BENEFITS
Whenever and wherever you logon to the Prodigy service, we
check to see if you've got the latest versions of a variety
of programs and data that reside in the STAGE. If not we
send you what you need. You don't have to ask for new
disks. And you don't have to reinstall.
RAMDISKS
Some members use RAMdisks to improve performance. A RAMdisk
is a "disk drive" made from memory (RAM) not from
mechanical parts. It's faster than its physical counterpart
but can more easily lose data. For that reason we don't
recommend using a RAMdisk. However here's something to
keep in mind if you're going to do it anyway. A RAMdisk is
volatile. If you turn your machine off, the information
stored on the RAMdisk evaporates. As you may be receiving
an update each time you sign on, be sure to save the
updates. To do this, copy the file named STAGE.DAT back to
your PRODIGY directory before you hit that switch.
NO UPDATE NEEDED
Members often ask about the need to update the PRODIGY
software on their PRODIGY installation disks. There is no
need to update the original installation disks. Use those
disks (or backup copies) to install the software on any
computer you use to sign on to the PRODIGY Service. Then,
when you sign on for the first time, the service will
automatically update the PRODIGY software.
DUAL COMPUTERS
Suppose you have two computers and use them both to access
the service. Let's say you use one more frequently than the
other. Each of your computers will get updates, if needed,
when you use them. The machine used most frequently will be
updated steadily (almost imperceptibly) by increments. When
you use the other machine, you might notice a delay during
logon because it's receiving a greater amount of updated
information all at once.
LIMITS
There's a practical limit to the kinds of changes we can
make automatically to an existing version of the software.
If you've ever tried adding air conditioning to a car you
bought without it, you'll understand this; sometimes it's
best to start over with the really useful options built in.
So over time when we make extensive improvements to the
PRODIGY software, we may send you a new set of disks.
NON-PRODIGY DATA
From time to time members using the DOS version of the
PRODIGY software see information from "other" (non-PRODIGY)
applications in the disk space used by STAGE.DAT.
Data from non-PRODIGY files is never actually part
of STAGE.DAT. More importantly it is never accessed or
uploaded by the PRODIGY software. There are two ways in
which extraneous data can appear in the STAGE. In the first
case, the data was originally located in areas of the hard
disk once used by other software. At one point in the past,
this data was erased.
DOS FILE DELETION
When you erase a file, PC-DOS or MS-DOS (the operating
system for personal computers) does not remove the file's
contents from your disk. Instead it only marks the space
used by the file as now "available for use". In doing this,
it gives other software permission to reuse that space.
Until that space is used by its new owner, the old data
remains. This is why certain "unerase" software packages
can recover accidentally deleted files. When you install the
PRODIGY software, it asks DOS to supply disk space for the
STAGE.DAT file. Depending on the size of the STAGE you
choose, this is usually a request for anywhere between
160Kb to 1 Mb.
DOS PROVIDES FILE SPACE
DOS then checks its inventory of available disk sectors,
finds the space and reserves it for its new owner:
STAGE.DAT. But DOS leaves any old data in that space
intact. Please keep in mind that DOS simply supplies the
sectors we request (as long as they are available) and does
not touch their original contents. Next, our install
program starts filling the space with blocks of PRODIGY
information. The PRODIGY install program does not erase any
old data because to do so would appreciably lengthen the
install process. As a result, old "erased" data may appear
in unused space following the blocks (where it's more
noticeable) as well as in smaller areas that occur within
the blocks (for more on this see "HOW WE USE SPACE" below).
ROOM TO SPARE
If you chose a large STAGE (anything from 250Kb to 950Kb),
chances are that at first, a portion of it will be unused.
It is likely that some of the space within that unused
portion was used by other software at one time. If so what
you'll see if you examine that area will be "leftovers".
Over time, the PRODIGY software will write blocks of
information to the STAGE replacing whatever is there.
Please keep in mind that the PRODIGY software can only
recognize the blocks of information that it puts into
STAGE.DAT itself. It does not read, collect, process or
transmit "non-PRODIGY data". All disk space containing such
data is treated as empty.
STANDARD TECHNIQUES
Like most major software, to ensure compatibility and
reliability when creating, reading and writing files, the
PRODIGY software employs standard "services" provided by
your computer's operating system. By viewing the STAGE with
certain software tools, members have observed information
from non-PRODIGY applications. However the PRODIGY software
can neither see this information nor use it. To the PRODIGY
software this space is considered "empty" and available for
storing PRODIGY data. Over time, as you use the service,
this "empty" space is covered by PRODIGY content.
HOW WE USE SPACE
When we store data in the STAGE, we do it via DOS in blocks
of a specific size. Let's say that size is 100 bytes. If we
store a 120 byte "object" then we use two blocks (or 200
bytes of storage). What we store takes up all of the first
block but only 20 bytes of the second block. What happens
to the remaining 80 bytes of the second block? Whatever was
there originally remains. If that block was built on a
previously used sector, 80 bytes of "old" data will be seen.
DATA FROM A DIFFERENT DISK
There's a second way in which extraneous data may appear
within the disk space used by the STAGE. When the STAGE is
being created, certain "control" areas may incorporate
information that was in your computer's memory (RAM). These
areas are used by the STAGE itself to keep track of its own
contents. This extraneous data may include non-erased data
or data from another disk. You may observe the names of
directories, your PATH, or information from the software
you were using just before you installed the PRODIGY
software. To minimize the occurrence of this data within
the STAGE, just turn your PC off, wait 15 seconds then turn
it on again before installing the PRODIGY software.
FOREVER SEPARATE
In short, extraneous information can appear in the disk
space used by the STAGE and yet not actually be part of it.
The appearance of this "non-PRODIGY data" is a side effect
of DOS file operations or the process by which the STAGE is
created. But, like a bottle containing oil and water, this
disk space STAGE can contain both PRODIGY and non-PRODIGY
data which are different and remain separate.
REMOVING EXTRANEOUS DATA?
The PRODIGY software does not read information created by
other software. And it does not read data other than its
own. Nevertheless some members have tried to delete
non-PRODIGY data from the STAGE by using file editors.
Modifying the contents of the STAGE file will do more harm
than good. To maintain the integrity of the STAGE, we use
special techniques that detect alteration of its contents.
"NO USER SERVICEABLE PARTS"
Changing the contents of the STAGE with a software tool
(like an editor) will render the STAGE unusable. You'll
have to reinstall the PRODIGY software. For those members
who are concerned by even the appearance of extraneous data
within the STAGE, we are preparing a utility to eliminate
non-PRODIGY data from the STAGE.
CONCLUSION
No extraneous information appearing within the disk space
used by STAGE.DAT is known to or used by PRODIGY.
The only information used by the PRODIGY software is what
is needed for the installation and operation of the
software.